Michigan surely has ED competitors. It is very interested both in attracting top students from out of state and sealing the deal with top Michiganders, and at Michigan’s quality level the students it wants most are surely thinking about ED at another top university or LAC if not SCEA at HYPS. Virginia is in the same boat, but because it doesn’t release “early” decisions until the end of January, it won’t lose any of its EA acceptees to ED elsewhere. All (or close enough to all to disregard the difference) of those applications will have been withdrawn before the decision become final.
I didn’t realize that USC – like the UCs – offers no early option at all. I was focusing on the bravery (or whatever) that Chicago formerly had, in letting students apply EA while they were also applying elsewhere ED. Besides Michigan, MIT and Caltech were the only other top-tier universities that did that, but I don’t think they face the same degree of competition from Columbia, Penn, Brown, or top LACs that Chicago and Michigan do. (Especially not Caltech, which is in UC-land where early is not the norm.)